Question: A goblet contains $7$ red marbles, $4$ green marbles, and $8$ blue marbles. If a marble is randomly chosen, what is the probability that it is not green?
There are $7 + 4 + 8 = 19$ marbles in the goblet. There are $4$ green marbles. That means $19 - 4 = 15$ are not green. The probability is $ \frac{15}{19}$.